• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.31 no.6
• /
• pp.36-44
• /
• 2003

In this paper, an analytic solution method is proposed to overcome the numerical problems when the slewing dynamics of hybrid coordinate systems is investigated via time finite element analysis. It is shown that the dynamics of the hybrid coordinate systems is governed by the coupled dual differential equations for both slewing and structural modes. Structural modes are transformed into the time-based modal coordinates and analytic spatial propagation equations are derived for each space-dependent time mode. Slew angle history is obtained analytically by appropriate applications of the boundary conditions and structural propagation is re-calculated using the slew angle. Numerical examples are demonstrated to validate the proposed analytic method in comparison to the existing state transition matrix method.

• Nutrition Research and Practice
• /
• v.4 no.3
• /
• pp.235-242
• /
• 2010

The objectives of this study were to examine the association between dietary factors and underweight and overweight adult Vietnamese living in the rural areas of Vietnam. A cross-sectional study of 497 Vietnamese aged 19 to 60 years (204 males, 293 females) was conducted in rural areas of Haiphong, Vietnam. The subjects were classified as underweight, normal weight, and overweight based on BMI. General characteristics, anthropometric parameters, blood profiles, and eating habits were obtained and dietary intake was assessed using 24-hour recalls for 2 consecutive days. A high prevalence of both underweight (BMI < 18.5 kg/$m^2$) and overweight (BMI ${\geq}$ 23 kg/$m^2$) individuals was observed (14.2% and 21.6% for males and 18.9% and 20.6% for females, respectively). For both genders, the overweight group were older than the under- and normal weight groups (P = 0.0118 for males and P = 0.0002 for females). In female subjects, the overweight group consumed significantly less cereals (P=0.0033), energy (P = 0.0046), protein (P = 0.0222), and carbohydrate (P = 0.0017) and more fruits (P = 0.0026) than the underweight group; however, no such differences existed in males. The overweight subjects overate more frequently (P = 0.0295) and consumed fish (P=0.0096) and fruits (P=0.0083) more often. The prevalence of both underweight and overweight individuals pose serious public health problems in the rural areas of Vietnamese and the overweight group was related to overeating and high fish and fruit consumption. These findings may provide basic data for policymakers and dieticians in order to develop future nutrition and health programs for rural populations in Vietnam.

• Journal of The Korean Association of Information Education
• /
• v.18 no.2
• /
• pp.203-212
• /
• 2014

With regard to recently emerged problems of smartphone addiction among adults and adolescents, this paper researched upper-grade elementary students depending on various demographic factors that have not been studied thoroughly so far. The survey was conducted on 1570 students in grades 4~6 of schools in Gyeonggi province. Results showed that, first, the average rate of smartphone ownership was about 66%. Second, about 1% of the students belonged to high-risk group, 5.7% to at-risk group, and normal user group was 93.3%. Third, based on the demographic factors, grade and academic achievements each was significantly correlated to the type of addiction group. For example, students with poor academic performance or in higher grade were more likely to be highly addictive. Fourth, both groups of at-risk and of normal-user pertaining to these factors - in urban areas, male students, sixth-grade, in dual income families - showed higher addictiveness score. But they were contrasted in the aspects of household economy and academic performance: at-risk group was more addictive in affluent families or excellent academic performance, whereas normal-user group had higher level of addictiveness in case of poor families or lower academic performance.

• Journal of the Korean Institute of Gas
• /
• v.2 no.3
• /
• pp.88-95
• /
• 1998

Vibration analysis of rotating machinery can give an indication of possible faults thus allowing maintenance before further damage occurs. Current predictive maintenance system installed in Pyung-tak has the ability to diagnose the mechanical problems within the LNG Pump when the vibration exceeds preset overall alarm levels. In this study, LNG pump auto-diagnosis system based upon Windows NT and DSP Board is developed. This system analysis velocity signal acquired from dual accelerometer input monitor system to diagnose pump condition. Many plots which display machine condition are shown and features of vibration are stored in every time. If the fault is found, the system diagnoses automatically using expert system and trend monitoring. Operator checks pump condition intuitively using personal computer monitor.

• Journal of Korean Elementary Science Education
• /
• v.25 no.1
• /
• pp.70-88
• /
• 2006

The purpose of this study is to investigate the effect of a multiple cognitive conflict strategy at remedying student's misconceptions. Elementary students have many misconceptions about the brightness of the electric bulb in simple dual circuits. Most of the misconceptions can be summed up as 'the more batteries or the fewer bulbs, the brighter is the output.' The students have learned about the brightness of the electric bulb while connected to a battery in Grade 4 and the brightness of multiple electric bulbs in Grade 5. However, about $50%$ of the students remain with the firm misconception that the brightness of the bulb is related to the number of source batteries. This strong misconception may not lead to a conceptual change in the case of only one cognitive conflict. This study used a multiple conflict strategy while tackling the cognitive conflicts in the students as they solved the problems many times. It involved 160 grade 5 students. The result was they often changed their misconceptions and used more scientific thinking than the same grade students of other schools. It remains to be seen if this success will transfer to other schools and students and we intend on studying further the differences in students regarding this learning process.

• Journal of Applied Tourism Food and Beverage Management and Research
• /
• v.10
• /
• pp.187-202
• /
• 1999

We desperately recognize from the economic situation in IMF crisis that only competive goods and serviced. It is anticipated that this difficult situation will probably be continued till 1999. Therefore, it is necessary to think over real aspects of eating=outdoors in IMF period and to provide an opportunity to confront with this crisis. Analysis a recent tendency of domestic eating-outdoors business, there appears, first of all, dual types of eating-outdoors; the one is a sort of 'Cost Sale', which provides some special menu with lowest prices, and the other is a type of 'Family Restaurant', which regards the atmosphere of the place as one of the most essential elements. Both types are getting more popular today. As the result, neither of the alternative cannot recover the current Depression. It is natural that no other conditions can compete with good tastes, fancy atmosphere, and good prices. As a matter of fact, however, it is quite difficult to run this type of bussiness adjusted the above whole conditions. Therefore owners of eating-house must decide to run either ' Cost Sale' or 'Family Restaurant' first and investigate some problems and conditions accordingly. In ane way, the owner intensively visits to some eating houses which is similar style in size and management to that of his style in size and management to that of his and look over what is good and what is bad Right after this investigation, it is efficient for he or she to improve his or her business style in size and management in a short period. It is helpful to check some complements; improvement of signboards, cleaning up of the interior, selecting suitable menu, adjusted prices, tastes, and service quality etc. Although eating-outdoors business is hard hit by IMF, We hope that it would rapidly be brisk in 2000, becaused by that time the basis of each industry would be high qualified, and rich technology would be accumulated.

• Journal of Energy Engineering
• /
• v.25 no.4
• /
• pp.1-6
• /
• 2016

Seawater desalination plants generally have two inherent problems which stem from energy inefficiency and desalination concentrate management. The former has been somewhat resolved thanks to the innovative methods in utilizing new and renewable energy resources whereas the latter still has much issues to be dealt with. This paper introduces the application of a desalting process for the disposal of desalination concentrate (especially, Mg) and to improve its cost effectiveness of a MVR seawater desalination plant built in Jeju. Principal component analysis on the desalination concentrate has revealed a steady reduction of Mg with the application of the desalting process verifying its functional reliability. Also, it was found that our MVR seawater desalination plant is not only energy efficient but also could be effectively applied for the dual purpose of fresh water production and concentrate management.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2007.10a
• /
• pp.657-660
• /
• 2007

In the present age, a vehicle works important part in our lives and economical domain that transport people, freights, and everything. And both of its number and value are increasing more and more. But user's convenience, control system could not be archived improvement than technological success. In this paper, we suggest some kinds of administrative agendas; simplifying executive processes, designing vehicle information system using by RFID which includes Ubiquitous skill and optical communication network. Especially, this paper suggests public vehicle control model which can simplify every executive processes of vehicle's life in the newest method. There are many kinds of RFID applicative products about transportation. And a dual invest should be interrupted for economical purpose. So this paper also proposes some way for problems of these types.

• The Korean Journal of Applied Statistics
• /
• v.25 no.1
• /
• pp.153-162
• /
• 2012

We proposed a mixed-mode design with a landline survey and mobile survey as the solution for the problems of election opinion polls by the original telephone survey method, mostly with limited population coverage for young people not living at home and with lower efficiency in selecting valid voters. We numerically verified the applicability of the proposed dual frame survey by analyzing the preliminary opinion poll results of the Seoul mayor by-election of October 26 2011. This research achieved the result that relative standard errors were similar between a mobile RDD sample and landline RDD sample though the variance was bigger in the former. Though the combination of mobile RDD and landline RDD is not found to improve the forecast accuracy, it still is expected to have higher reliability for election polls by expanding the population coverage and compensating the weakness of each survey method.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.19 no.12
• /
• pp.1322-1328
• /
• 2009

This paper presents vibration analysis of maskless exposure module in printed circuit board(PCB) manufacturing system. In order to complete exposure process in PCB, masking type module has been widely used in electronics industries. However, masking process confronts some limitations of application due to higher production cost for masking as well as lower printing resolution. Therefore, maskless exposure module is started to be in the spotlight for flexible production system to meet the needs of fabrication in variable patterns at low cost. Since maskless exposure process adopts direct patterning to PCB, vibration problems become more critical compared to conventional masking type process. Moreover, movements of exposure engine as well as stage generate vibration sources in the system. Thus, it is imperative to analyze the vibration characteristics for the maskless exposure module to improve the quality and accuracy of PCB. In this study, vibration analysis using the finite element analysis is conducted to identify the critical structural parts deteriorating vibration performance. Also, Experimental investigations are conducted by single/dual encoder measurement process under the operating module speed. Measurement points of vibration are selected by three places, which are base of stage, exposure engine and top of stage, to check the effect of vibration from the exposure engine. Comparisons between analysis results and experimental measurement are conducted to confirm the accuracy of analysis results including the developed FE model. Finally, this studies show feasibility of optimal design using the developed FE analysis model.